Problem: Gabriela had to read papers 31 through 52 for homework tonight. If Gabriela read all of the papers she was assigned, how many papers did she read?
Explanation: Instead of counting papers 31 through 52, we can subtract 30 from each number so we instead consider papers 1 through 22. We see that Gabriela read 22 papers. Notice that she read 22 and not 21 papers.